"The civil servants will stage the strike at all ministries and government institutions in Gaza," the union said in a statement.
The Palestinian national unity government held its weekly meeting in the Gaza Strip on Tuesday, a day after several ministers arrived in the blockaded Palestinian territory.
Government spokesperson Ehab Bessaiso said the government had discussed all pending issues during its meeting, including the case for thousands of Hamas-employed civil servants who have not taken their salaries for several months now.
He added that civil servants employed before Hamas took control of Gaza in 2007 would start to gradually go back to work.
He added that the government would then enlist the services of some of the workers employed by Hamas, noting that the employment of civil servants should happen in the light of Palestinian laws.
Earlier in the day, scores of Gaza Strip workers staged a protest outside the meeting place of the government to demand their overdue salaries.
Some 40,000 civil servants employed by the Hamas government stopped receiving salaries soon after the formation of the Palestinian unity government in June.
The unity government was formed in the light of an April reconciliation agreement between Hamas and rival Palestinian faction Fatah.
The new government, however, has yet to assume political control of the Gaza Strip, impeding the payment of the territory's civil servants.